Thermoelectric module

ABSTRACT

An objective of the present invention is to provide a thermoelectric module which can achieve high heat release and heat absorption efficiencies and which can obviate any thermal stress-caused damages. A thermoelectric module ( 1 ) in an embodiment has a predetermined number of thermoelectric semiconductor elements P and N which are arranged in a flat plate configuration. Each of the thermoelectric semiconductor elements P and N has on one face thereof a one-side electrode ( 2 ) and has on the other face thereof an other-side electrode ( 3 ), thereby allowing all of the thermoelectric semiconductor elements P and N to be connected in series. The one-side electrodes ( 2, 2  . . . ) have heat release/heat absorption fins (heat transfer fins) ( 2 F,  2 F . . . ) and the other-side electrodes ( 3, 3  . . . ) have heat release/heat absorption fins (heat transfer fins) ( 3 F,  3 F . . . ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermoelectric module in which apredetermined number of thermoelectric semiconductor elements arearranged in a flat plate configuration, each of the thermoelectricsemiconductor elements has on one face thereof a one-side electrodes andhas on the other face thereof an other-side electrodes, and all of thethermoelectric semiconductor elements are connected in series.

2. Description of the Related Art

A conventional thermoelectric apparatus A shown in FIG. 8 is configuredby allowing both faces of a thermoelectric module M (a heat absorptionface and a heat release face) to have heat sinks F having fins.

The thermoelectric module M is configured such that a predeterminednumber of thermoelectric semiconductor elements (P-type elements andN-type elements) P and N are arranged in a flat plate configuration toallow these thermoelectric semiconductor elements P and N to have on oneface (an upper face in FIG. 8) one-side electrodes Ta, Ta . . . and tohave on the other face (a lower face in FIG. 8) other-side electrodesTb, Tb . . . , thereby allowing all of the thermoelectric semiconductorelements P and N to be connected in series.

On the other hand, the heat sinks F having fins are provided for thepurpose of increasing the heat absorption and release efficiencies ofthe thermoelectric module M, and are generally formed of a metalmaterial having a high thermal conductivity such as aluminum or thelike.

The pair of heat sinks F, F is attached to a predetermined position suchthat bolts B, B are used to fasten the pair of heat sinks F, F to eachother with the thermoelectric module M being sandwiched by the pair ofheat sinks F, F.

Furthermore, insulators G formed of ceramic or the like for anelectrical insulation purpose are interposed between the one-sideelectrodes Ta at the thermoelectric module M and the heat sink F formedof a metal material as described above and between the other-sideelectrodes Tb at the thermoelectric module M and the heat sink F,respectively.

In the above-described conventional thermoelectric apparatus A, theinsulator G is provided between the thermoelectric module M and each ofthe heat sinks F. This caused an inconvenience in that thethermoelectric module M and each of the heat sinks F have therebetweenan increased thermal resistance, resulting in a decrease in the heatrelease and heat absorption efficiencies of the thermoelectric module M.

One of the conceivable configurations for eliminating theabove-described inconvenience is the one in which each heat sink F isformed of non-electrically-conductive material such as resin toeliminate the need for the insulator G. Such a configuration, however,has a difficulty in eliminating the decrease in the heat release andheat absorption efficiencies of thermoelectric module M becausenon-electrically-conductive material has a higher thermal resistancethan metal materials.

The above-described conventional thermoelectric apparatus A has, on theother hand, has other problems. One of the problems is that, during theoperation of the thermoelectric apparatus A, the heat sink F attached tothe heat absorption face and the heat sink F attached to the heatrelease face of the thermoelectric module M have a temperaturedifference to cause a thermal stress which affects the thermoelectricmodule M, resulting in a reduced life of the thermoelectricsemiconductor elements P and N or a damaged thermoelectric module M orthe like.

The present invention is made in view of the above and has an object ofproviding a thermoelectric module which can achieve high heat releaseand absorption efficiencies and which can obviate any damages caused bythermal stress.

SUMMARY OF THE INVENTION

A thermoelectric module according to the present inventions in which apredetermined number of thermoelectric semiconductor elements arearranged in a flat plate configuration, each of the thermoelectricsemiconductor elements has on one face thereof one-side electrodes andhas on the other face thereof other-side electrodes so that all of thethermoelectric semiconductor elements are connected in series, ischaracterized in that a least one of the one-side electrodes and theother-side electrodes are provided with heat transfer fins.

In a thermoelectric module according to the present invention, apredetermined number of thermoelectric semiconductor elements arearranged in a flat plate configuration, each of the thermoelectricsemiconductor elements has on one face thereof a one-side electrodes andhas on the other face thereof an other-side electrodes, and all of thethermoelectric semiconductor elements are connected in series, thethermoelectric module is characterized in that at least one of eachelectrode of the one-side electrodes or each electrode of the other-sideelectrodes has thereon heat transfer fins.

According to the above configuration, the direct provision of the heattransfer fins on one-side electrodes and other-side electrodeseliminates the need of an insulator that has been interposed between aheat sink having fins and a thermoelectric module in the conventionalapparatus, thereby to eliminate a thermal resistance caused by such aninsulator. Thus, the thermoelectric module according to the presentinvention can provide a remarkable increase in heat release and heatabsorption efficiencies.

Further, according to the above configuration, the direct provision ofthe heat transfer fins on the one-side electrodes and the other-sideelectrodes also prevents a thermal stress which is caused in aconventional apparatus in which a thermoelectric module is sandwiched bya pair of heat sinks through bolts. Thus, the thermoelectric moduleaccording to the present invention also prevents unexpected thermalstress.

Therefore, the thermoelectric module according to the present inventioncan achieve high heat release and heat absorption efficiencies and canobviate any thermal stress-caused damages.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1(a) is a total plan view illustrating an embodiment of athermoelectric module according to the present invention.

FIG. 1(b) is a cross-sectional side view illustrating the embodiment ofthe thermoelectric module according to the present invention.

FIG. 2 is a cross-sectional side view illustrating another embodiment ofthe thermoelectric module according to the present invention.

FIG. 3 is a principle diagram illustrating a mechanism by which heat ofcondensation is transferred by a surface tension effect by low fins.

FIG. 4 is a diagram illustrating an effect by the low fins to acceleratethe transfer of the heat of condensation.

FIG. 5(a) is a partial cross-sectional view illustrating a modifiedexample of the low fins of the thermoelectric module shown in FIG. 2.

FIG. 5(b) is a partial cross-sectional view illustrating a modifiedexample of the low fins of the thermoelectric module shown in FIG. 2.

FIG. 5(c) is a partial cross-sectional view illustrating a modifiedexample of the low fins of the thermoelectric module shown in FIG. 2.

FIG. 5(d) is a partial cross-sectional view illustrating a modifiedexample of the low fins of the thermoelectric module shown in FIG. 2.

FIG. 6 is cross-sectional side view illustrating another embodiment ofthe thermoelectric module according to the present invention.

FIG. 7 is a cross-sectional side view illustrating another embodiment ofthe thermoelectric module according to the present invention.

FIG. 8 is a side view illustrating a thermoelectric apparatus using aconventional thermoelectric module.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings.

FIGS. 1(a) and 1(b) illustrate an embodiment of a thermoelectric moduleaccording to the present invention. This thermoelectric module 1 isconfigured such that, a predetermined number of thermoelectricsemiconductor elements (P-type elements and N-type elements) P and N arearranged in a flat plate configuration to allow these thermoelectricsemiconductor elements P and N to have on one face (upper face in FIG.1(a)) one-side electrodes 2, 2 . . . and to have on the other face(lower face in FIG. 1(b)) other-side electrodes 3, 3 . . . , therebyallowing all of the thermoelectric semiconductor elements P and N to beconnected in series.

In this embodiment, the predetermined number of thermoelectricsemiconductor elements P and thermoelectric semiconductor elements N arealternatively arranged to form a lattice pattern. Each of thesethermoelectric semiconductor elements P and N is solder-connected toeach electrode of the one-side electrodes 2 and the other-sideelectrodes 3. Furthermore, interspaces among the thermoelectricsemiconductor elements P and N are filled with insulators 4 which areformed of a mold resin or a silicon sealant having low thermalconductivity.

As shown in FIGS. 1(a) and 1(b), the one-side electrodes 2 have arectangular-shaped base section 2B connected to the thermoelectricsemiconductor elements P and N; and a number of fins for heatrelease/heat absorption functions (heat transfer fins) 2F, 2F . . .which are provided on an outer face of the base section 2B (upper faceof FIG. 1(b)). The base section 2B and each of the fins 2F, 2F . . . areformed in one united body by a metal material having good electricalconductivity and high thermal conductivity such as copper (Cu) oraluminum (Al).

As with the above-described one-side electrodes 2, the other-sideelectrodes 3 also have a rectangular-shaped base section 3B connected tothe thermoelectric semiconductor elements P and N; and a number of finsfor heat release/heat absorption functions (heat transfer fins) 3F, 3F .. . which are provided on an outer face of the base section 3B (lowerface of FIG. 1(b)). The base section 3B and each of the fins 3F, 3F . .. are formed in one united body by a metal material having goodelectrical conductivity and high thermal conductivity such as copper(Cu) or aluminum (Al).

According to the thermoelectric module 1 having the above-describedconfiguration, the fins 2F and the fins 3F are directly provided on theone-side electrodes 2 and the other-side electrodes 3. This directprovision of fins eliminates the thermal resistance caused by theinsulator in the conventional apparatus (see FIG. 8) in which theinsulator has been interposed between the heat sink having fins and thethermoelectric module, thereby to provides a remarkable increase in theheat release and heat absorption efficiencies in the thermoelectricmodule 1.

According to the thermoelectric module 1 having the above-describedconfiguration, the one-side electrode 2 and the other-side electrodes 3are formed of a metal material such as copper (Cu) or aluminum (Al)having good electric conductivity and high thermal conductivity (i.e.,low thermal resistance). This also provides a further increase in theheat release and heat absorption efficiencies of the thermoelectricmodule 1.

According to the thermoelectric module 1 having the above-describedconfiguration, the fins 2F and the fins 3F are directly provided on theone-side electrodes 2 and the other-side electrodes 3. Thus, unlike theconfiguration of the conventional apparatus (see FIG. 8) in which athermoelectric module is sandwiched by a pair of heat sinks throughbolts, the configuration according to this embodiment is free from thethermal stress generated in the conventional configuration.Specifically, the thermoelectric module 1 is not subjected toundesirable thermal stress during the operation, thereby allowing thethermoelectric module 1 to obviate any thermal stress-caused damages andto have an improved durability.

Further, since the heat sinks is not used as in the conventionalapparatus (see FIG. 8), the thermoelectric module 1 has a very compactexterior and a simple structure, thereby enabling a very goodmanufacturability.

In addition, the one-side electrodes 2 and the other-side electrodes 3of the above-described thermoelectric module 1 have the flat rectangularbase section 2B and base section 3B on which the fins 2F and fins 3F areformed. This configuration provides the thermoelectric semiconductorelements P and N, and the one-side electrodes 2 and the other-sideelectrodes 3 with sufficient connection areas therebetween by the basesection 2B and the base section 3B, thereby allowing the thermoelectricmodule 1 to have the equal structural reliability to that of theconventional thermoelectric modules.

In the above-described embodiment, the one-side electrodes 2 and theother-side electrodes 3 have fins which align with one another in thedirection of the shorter edges of the electrodes and which stand withinterspaces thereamong in the direction of the longer edges of theelectrodes.

In the above-described embodiment, the fins provided on the one-sideelectrodes 2 and the other-side electrodes 3 generally have a thin flatplate configuration. However, it goes without saying that pin fins mayalso be used in place of these thin plate fins.

The fins 2F and the fins 3F formed on the one-side electrodes 2 and theother-side electrodes 3 provide an effect for expanding a heat transfersurface area against single-layer fluid such as liquid or gas, therebyapparently increasing the heat release and heat absorption efficienciesof the one-side electrodes 2 and the other-side electrodes 3. However,it is noted that in designing the fins 2F and the fins 3F, fin sizes(height, thickness, configuration, etc.) should be determined by takinginto consideration a fin efficiency.

FIG. 2 shows another embodiment of the thermoelectric module accordingto the present invention. This thermoelectric module 10 allows heat torelease from a heat medium provided on the heat absorption-side throughcondensation.

A one-side electrode 12 has a rectangular-shaped base section 12Bconnected to the thermoelectric semiconductor elements P and N; and amultitude of low fins (heat transfer fins) 12F, 12F . . . provided onthe outer face of the base section 12B (upper face in FIG. 2). The basesection 12B and each of the low fins 12F, 12F . . . are formed in oneunited body with a metal material having good electrical conductivityand high thermal conductivity such as copper (Cu) or aluminum (Al).

The low fins 12F, 12F . . . have a structure which provides not onlytheir original effect of expanding a heat transfer surface area but alsoan additional effect obtained from a surface tension of the heat medium,thus achieving a remarkable increase in a condensation heat transfercoefficient. The low fins 12F, 12F . . . generally have a configurationof a height of 5 mm or less and a pitch of 10 mm or less (space of 5 mmor less).

A principle of how the surface tension of the heat medium acceleratesthe condensation heat transfer coefficient will now be described. Asshown in FIG. 3, a pressure Pt in the interior of condensate having aconvex liquid surface configuration at the top free end of the low fin12F is higher than the atmospheric pressure as shown in the followingformula (1), and a pressure Pb in the interior of condensate having aconcave liquid surface configuration at the groove sections among theneighboring low fins 12F is lower than the atmospheric pressure as shownin the following formula (2). As a result, the difference between thepressure Pt and the pressure Pb as shown by the following formula (3)allows the condensate to be driven from the top free end of the low fins12F to the groove sections among the neighboring low fins 12F in thedirection of arrows f, f . . . , as shown the in FIG. 3. This results ina thinner condensate at the surface of the low fins 12F, therebyproviding a higher condensation heat transfer coefficient.

Pt=Pa+(σ/Rt)  (1)

Pb=Pa−(σ/Rb)  (2)

ΔP=Pt−Pb=σ[(1/Rt)+(1/Rb)]  (3)

In the above formulas, Rt is a radius of curvature of the condensate atthe top free end of the low fins 12F, Rb is a radius of curvature of thecondensate at the groove sections among the neighboring low fins 12F,and Pa is the atmospheric pressure.

FIG. 4 shows the effect, which is brought about by the low fins, ofaccelerating the condensation heat transfer coefficient when Fluorinert® is used as a heat medium (condensate). As shown in FIG. 4, when a heattransfer temperature difference DT (a difference in temperature betweena heat medium vapor and a heat transfer surface) is DT=20° C., a pitch pbetween fins is p=0.6 mm, and a fin height “h” is h=1 mm, then the lowfins allow about 14 times larger condensation heat transfer coefficientas compared to that with flat plate.

The configuration of the thermoelectric module 10 shown in FIG. 2 isbasically the same as that of the thermoelectric module 1 shown in FIGS.1(a) and 1(b) except that the one-side electrodes 12 have the low fins12F, 12F . . . . Thus, components constituting the thermoelectric module10 in FIG. 2 that have the same functions as those of correspondingcomponents in FIGS. 1(a) and 1(b) are shown with reference numeralsgained by adding ten to each of reference numerals of such componentsshown in FIGS. 1(a) and 1(b), and the description thereof is omitted.

The thermoelectric module 10 having the above-described configurationcan also achieve the same functions and effects as those given by thethermoelectric module 1 shown in FIGS. 1(a) and 1(b) in terms of thehigh heat release and absorption efficiencies and the prevention ofthermal stress-caused damages, etc.

In the one-side electrode 12 of the above-described embodiment, the lowfins 12F align with one another in the direction of the shorter edges ofthe electrodes and stand with interspaces thereamong in the direction ofthe longer edges of the electrodes.

In the above-described embodiment, each of the low fins 12F of theone-side electrodes 12 forms an elongate projection. However, the lowfins 12F may also be formed by a group of pins.

It is also noted that the design of the low fins 2F of the one-sideelectrodes 12 should be determined so that optimum surface tensioneffect can be obtained by the determined pitch (space), height, shape orthe like of the fins.

It is also noted that the low fins 2F of the one-side electrodes 12 mayhave various shapes other than the shape of the low fin 12Fa shown inFIG. 5(a), such as a trapezoidal shape of a low fin 12Fb shown in FIG.5(b), a triangular shape of a low fin 12Fc shown in FIG. 5(c), or acurved shape of a low fin 12Fd shown in FIG. 5(d).

FIG. 6 shows another embodiment of the thermoelectric module accordingto the present invention. This thermoelectric module 20 is cooled byelectrically conductive fluid such as water.

Each of other-side electrodes 23 is constructed by a rectangular flatplate which is connected to each of thermoelectric semiconductorelements P and N. The other-side electrodes 23, 23 . . . have, on theouter face thereof (lower face in FIG. 6), a water jacket 25 via aninsulation layer 26 providing electrical insulation. The water jacket 25allows electrically conductive fluid (e.g., water) to be suppliedthereinto and circulated therethrough, and is formed of a metal materialhaving high thermal conductivity such as copper (Cu) or aluminum (Al).

The above-described configuration of the thermoelectric module 20 isbasically the same as that of the thermoelectric module 1 shown in FIGS.1(a) and 1(b) except that the other-side electrodes 23, 23 . . . areconstructed by flat plates and have the water jacket 25 via theinsulation layer 26. Thus, components constituting the thermoelectricmodule 20 in FIG. 6 that have the same functions as those ofcorresponding components in FIGS. 1(a) and 1(b) are shown with referencenumerals gained by adding twenty to each of reference numerals of suchcomponents shown in FIGS. 1(a) and 1(b), and the description thereof isomitted.

The thermoelectric module 20 having the above-described configurationcan also achieve the same functions and effects as those given by thealready-described thermoelectric modules 1 and 10, in terms of high heatrelease and heat absorption efficiencies and the prevention of thermalstress-caused damages, etc.

FIG. 7 shows another embodiment of the thermoelectric module accordingto the present invention. This thermoelectric module 30 releases heatfrom a heat medium on the heat absorption side by means of condensation,and to be cooled by using electrically conductive fluid such as water.

Each of other-side electrodes 33 is constructed by a rectangular flatplate which is connected to each of thermoelectric semiconductorelements P and N. The other-side electrodes 33, 33 . . . has, on theouter face thereof (lower face in FIG. 7), a water jacket 35 via aninsulation layer 36 providing electrical insulation. The water jacket 35allows electrically conductive fluid (e.g., water) to be suppliedthereinto and circulated therethrough, and is formed of a metal materialhaving high thermal conductivity such as copper (Cu) or aluminum (Al).

The above-described configuration of the thermoelectric module 30 isbasically the same as that of the thermoelectric module 10 shown in FIG.2 except that each of the other-side electrodes 33, 33 . . . has a flatplate shape and the other-side electrodes 33, 33 . . . have the waterjacket 35 via the insulation layer 36. Thus, components constituting thethermoelectric module 30 in FIG. 7 that have the same functions as thoseof corresponding components in FIG. 2 are show with reference numeralsgained by adding twenty to each of reference numerals of such componentsshown in FIG. 2, and the description thereof is omitted.

The thermoelectric module 30 having the above-described configurationcan also achieve the same functions and effects as those given by thealready-described thermoelectric modules 1, 10, and 20 in terms of highheat release and heat absorption efficiencies and the prevention ofthermal stress-caused damages, etc.

What is claimed is:
 1. A thermoelectric module, which comprises: aplurality of thermoelectric semiconductor elements being arranged in aflat plate configuration and having one side face and another side face,a first side electrode directly connected to entirety of the one sideface of the thermoelectric semiconductor elements, a second sideelectrode directly connected to entirety of the another side face of thethermoelectric semiconductor elements, at least one of the first sideelectrode and the second side electrode having a rectangular shape, anda multiplicity of heat transfer fins integrally formed on said at leastone of the first side electrode and the second side electrode having therectangular shape, so that the fins are parallel to a shorter side ofthe rectangular shape.
 2. The thermoelectric apparatus according toclaim 1, wherein at least one fin of the multiplicity of heat transferfins is integrally formed on an interior portion of the rectangularshape of said at least one of the first side electrode and the secondside electrode having the rectangular shape, so that the least one finis spaced from the shorter sides of the rectangular shape.
 3. Athermoelectric apparatus, which comprises: a thermoelectric modulecomprising a plurality of thermoelectric semiconductor elements beingarranged in a flat plate configuration and having one side face andanother side face, a first side electrode directly connected to all ofthe one side face of the thermoelectric semiconductor elements, a secondside electrode directly connected to all of the another side face of thethermoelectric semiconductor elements, at least one of the first sideelectrode and the second side electrode having a shape of rectangular,and a multiplicity of heat transfer fins integrally formed on said atleast one of the first side electrode and the second side electrodehaving the rectangular shape, so that the fins are parallel to a shorterside of the rectangular shape, and heat medium that condenses at theheat transfer fins of the thermoelectric module.
 4. The thermoelectricapparatus according to claim 3, wherein at least one fin of themultiplicity of heat transfer fins is integrally formed on an interiorportion of the rectangular shape of said at least one of the first sideelectrode and the second side electrode having the rectangular shape, sothat the least one fin is spaced from the shorter sides of therectangular shape.
 5. A thermoelectric apparatus, which comprises: athermoelectric module comprising a plurality of thermoelectricsemiconductor elements being arranged in a flat plate configuration andhaving one side face and another side face, a first side electrodedirectly connected to all of the one side face of the thermoelectricsemiconductor elements, a second side electrode directly connected toall of the another side face of the thermoelectric semiconductorelements, and a multiplicity of heat transfer fins integrally formed onat least one of the first side electrode and the second side electrode,and heat medium that condenses at the heat transfer fins of thethermoelectric module, wherein the heat transfer fins are of thin platehaving a height of 5 mm or less and a pitch of 10 mm or less withadjacent fins being spaced apart by 5 mm or less.